Originally Posted by ArmoryDoc
Staggering rounds is never a good idea as it can affect function of the gun. You're better off carrying a mag with different rounds in it. Don't worry about inflicting "pain". Worry about your accuracy and shot placement in the face of tremendous stress. Twenty five yards from an active shooter will feel like 25". You better be good at stress management.
But if both rounds are 155 grain and have a similar nose shape and same overall length surely that's pretty close to the same bullet as far as gun functionality is concerned.